On Wed, Oct 31, 2018 at 9:41 AM Rajat Srivastava rajat.srivastava@nxp.com wrote:
-----Original Message----- From: Simon Goldschmidt simon.k.r.goldschmidt@gmail.com Sent: Wednesday, October 31, 2018 2:06 AM To: Rajat Srivastava rajat.srivastava@nxp.com; u-boot@lists.denx.de Cc: jagan@openedev.com Subject: Re: [U-Boot] [PATCH 0/3] Read SFDP parameters and access flash above 16MB
On 17.10.2018 13:27, Rajat Srivastava wrote:
Add functionality to read and parse SFDP parameters to auto-detect flash size, page size and address width of flash. This enables flash access above 16MB using 4-byte addressing mode.
Add driver support to get SFDP information of flash and use it to access flash above 16MB.
Enable reading and parsing of SFDP parameters for Spansion's s25fs512 flash to auto-detect its size, its page size and the addressing mode it supports.
Why do you need driver-specific code to read the sfdp parameters? Wouldn't it be much cleaner to solve this from spi_flash.c only?
That would have been cleaner only if it was possible. To read SFDP parameters of any flash, a READ_SFDP (0x5A) command needs to be sent to flash.
The mtd framework does not allow sending any command to any flash directly from mtd layer. Any transaction initiated from mtd framework will call spi_xfer() function of the respective SPI driver which will further send the actual command to flash.
Linux has also implemented reading SFDP parameters functionality in a similar way.
I don't know the Linux way. I only looked at the driver my platform uses (cadence_qspi) and I can't match this to your driver. The cadence driver more or less sends 'dout' as command, so using 'spi_flash_read_common()' in spi_flash.c should work. Is this different in your driver?
If so, just adding the 'spi_flash_parse_sfdp()' function on top of Stefan's patch should work?
I tried testing this patch, but just like for Stefan, but it just didn't work for me and I failed to see some simple steps to adjust my spi driver to make it work.
You can see these patches for SFDP implementation in SPI driver: https://patchwork.ozlabs.org/patch/985329/ https://patchwork.ozlabs.org/patch/985328/
Well, of course I saw those patches. As written above, I had a hard time adapting your fsl_qspi changes to the cadence_qspi driver and I think it would be better if this wasn't needed.
Simon
You, basically, need to send:
- 0x5A command (READ_SFDP command)
- 3-byte address (address will be provided by framework)
- 8 dummy cycles
Simon
Rajat Srivastava (3): mtd/spi: Add JEDEC SFDP support in SPI framework fsl_qspi: Access flash above 16MB using SFDP spi_flash_ids: Enable SFDP parsing for s25fs512 flash
drivers/mtd/spi/sf_internal.h | 4 + drivers/mtd/spi/spi_flash.c | 297
+++++++++++++++++++++++++++++++++++++---
drivers/mtd/spi/spi_flash_ids.c | 3 +- drivers/spi/fsl_qspi.c | 103 +++++++++++++- include/spi.h | 2 + include/spi_flash.h | 120 ++++++++++++++++ 6 files changed, 501 insertions(+), 28 deletions(-)